Combined tachometer and maximum speed limiting device

ABSTRACT

A combined tachometer and maximum speed limiting device for cutting off the engine of a hot rod vehicle for a predetermined short time interval upon reaching a predetermined limiting speed to signal to the driver that the transmission should be shifted to the next higher gear and to provide time to make the shift. A tachometer receiver in the form of a meter type relay provides contacts which are closed at a set maximum engine speed. The meter coil is energized by variable direct voltage from a tachometer transmitter which is coupled to the primary of the ignition coil of the vehicle. Closure of the meter contacts energizes an output relay having contacts which are connected to short out the ignition system. Capacitor discharge means are provided for insuring positive closure of the meter contacts and for delaying drop-out of the output relay for a predetermined but adjustable time interval. In an alternate embodiment means are provided for cutting out the engine until intentionally reset.

United States Patent Westberg 1541 COMBINED TACHOMETER AND MAXIMUM-SPEEDLIMITING DEVICE [72] Inventor: Vernon C. Westberg, 22 S. State, Elgin,111.

[22] Filed: Feb. 8, 1971 [21] Appl.No.: 113,170

[52] U.S.Cl ..123/118, 123/102 July 4, 1972 Primary ExaminerLaurence M.Goodridge AttorneyWolfe, Hubbard, Leydig, Voit & Osann [57] ABSTRACT Acombined tachometer and maximum speed limiting device for cutting offthe engine of a hot rod vehicle for a predetermined short time intervalupon reaching a predetermined limiting speed to signal to the driverthat the transmission should be shifted to the next higher gear and toprovide time to make the shift. A tachometer receiver in the form of ameter type relay provides contacts which are closed at a set maximumengine speed. The meter coil is energized by variable direct voltagefrom a tachometer transmitter which is coupled to the primary of theignition coil of the vehicle. Closure of the meter contacts energizes anoutput relay having contacts which are connected to short out theignition system. Capacitor discharge means are provided for insuringpositive closure of the meter contacts and for delaying drop-out of theoutput relay for a predetermined but adjustable time interval. ln analternate embodiment means are provided for cutting out the engine untilintentionally reset.

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COMBINED TACIIOMETER AND MAXIMUM SPEED LIMITING DEVICE In the operationof hot rod vehicles to achieve maximum acceleration over a measuredcourse it is desirable to rev" the engine up to a maximum limit r.p.m.in each gear in the most rapid possible succession. Since the maximumlimit r.p.m. is just short of that which may produce self destruction ofthe engine, the driver must be highly skilled and must watch thetachometer closely to avoid exceeding the limiting r.p.m. in each of thegears. This constitutes a burden upon the driver and runs a severe riskthat a costly engine may, through a momentary inadvertence, be damagedby over-revving." Efforts have been made in the past to provideautomatic means for limiting the engine speed, but prior devices havenot been reliable and have been characterized by a dropping off in thepower of the engine as the limiting speed is approached.

Accordingly it is an object of the invention to provide a maximum speedlimiting device which is highly precise and reliable, which can bedepended upon to cut off the engine at a precise r.p.m., and whichmaintains the engine cut off for a precisely predetermined butadjustable fraction of a second, in any event a length of time justadequate to permit manual shifting from one gear to the next. It is animportant object to provide an improved speed limiting device employinga meter type relay but which avoids the indecisive, chattering contactgenerally associated with such relays and which provides, instead, apositive and immediate low resistance contact for prompt energization ofan output relay having ignition-shorting contacts.

It is a more specific object of the present invention to provide acombined tachometer and maximum speed limiting device in which atentative making of contact in the meter relay triggers discharge of acapacitor into the meter coil in an additive sense so as to urge themeter contacts more forcefully together for minimum contact resistance.It is a related object to employ subsequent charging of the capacitor,by passage of the charging current through the associated output relay,to prevent dropout of the relay for a predetermined, short butadjustable time interval.

It is yet another object of the present invention to provide anauxiliary capacitor which is normally in the discharged state but whichis charged upon the making of contact in the meter relay andsubsequently, upon opening of the meter relay, discharged through thecoil of the output relay for further inhibiting drop-out.

It is another object of the invention in one of its aspects to provide amaximum speed limiting device employing an improved meter type relay inwhich the movable contact serves as a counterbalancing weight for theneedle of the meter in addition to performing its contact function.

It is still another object of the present invention to provide a maximumspeed limiting device which employs the transmitting and receivingelements of a conventional tachometer system and which achieves thespeed limitation and a precise de-powered interval with relatively minormodification of the existing components and at minor additional expense.It is an object of the invention to provide a combined tachometer andmaximum speed limiting arrangement which permits the engine to be fullypowered up to the instant that the predetermined maximum r.p.m. isreached and zero-powered for a predetermined time interval thereafter,following which full power is again available, and which consequentlyavoids the erratic operation and missing which characterizes theprevious efforts to secure speed limitation.

It is a related object to provide a combined tachometer and speedlimiting arrangement which is as easily installed as a conventionaltachometer of the electrical type, requiring only the addition of asingle wire leading from the receiving unit to the primary terminal ofthe ignition coil.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIG. I is a schematic diagram showing the power train and ignitionsystem of a typical hot rod vehicle with the present tachometer andspeed limiting device connected thereto.

FIG. 2 is a schematic electrical diagram of the transmitter and receiverportions of the tachometer-limiter system.

FIG. 2a is a diagram corresponding to FIG. 2 showing the making ofcontact in the meter and subsequent capacitor discharge.

FIG. 2b corresponds to FIG. 2a and shows the resulting closure of therelay occurring immediately thereafter to produce engine cut-ofl' andcharging of the auxiliary capacitor.

FIG. 20 shows opening of the meter contacts, with the relay being heldin by charging of the main capacitor and discharging of the auxiliarycapacitor.

FIG. 3 is an isometric, fragmentary, and partially exploded, view of themeter relay assembly.

3a is a fragment showing the making of contact in the meter relay.

FIG. 4 is a schematic diagram of a modification of the circuit providingspeed limitation but which requires manual resetting FIG. 5 is aschematic diagram showing a modification in which capacitor rush currentis used in the opposite sense.

While the invention is described in connection with certain preferredembodiments, it will be understood that I do not intend to be limited tothe particular embodiment shown but intend, on the contrary, to coverthe various alternative and equivalent constructions included within thespirit and scope of the appended claims.

Turning now to FIG. 1 there is shown, in diagrammatic form, a hot rodvehicle 10 having front wheels 11 and rear wheels 12. The later aredriven by a power train including an engine 15, a clutch l6,transmission 17 and difierential 18. The ignition system, indicated at20, includes an ignition coil having a primary 2] and high voltagesecondary 22. The primary is fed by a switch 23 from the regular vehiclebattery 24. The flow of current is interrupted by breaker points 25operated by a cam 26 having a connection 27 to the engine. The highvoltage from the secondary winding 22 is applied to the spark plugs viaa distributor 28 having a mechanical con nection 29 to the engine. Thetachometer and maximum speed limiting device includes a transmitter Tand receiver R, the latter having an indicating meter type relay M towhich more detailed reference will be made. A disabling line D extendsfrom the receiver to the junction between the primary winding 21 and thebreaker points 25.

Referring next to FIG. 2, the transmitter T will be seen to Consist of arelay 30 having a double throw contact blade 31 which makes normalcontact with an upper contact 32 and which is, upon energization, drawndownwardly against the lower contact 33. Connected to the lower contact33 is a batter 34 which may, for example, be of the long-lived mercurytype. Connected to the central terminal 31 is a commutated capacitor 35.The contact 32 and the right hand end of the capacitor 35 are connectedto output lines 36, 37. Each time the points open, a closing pulse isapplied to the relay winding 30 causing the capacitor 35 to becommutated back and forth from the battery 34 to the output lines 36, 37and with the current in the output lines being proportional to the speedof commutation, i.e., to the speed of the engine. For direct andconstant indication of speed the receiver R includes meter M which maybe of dArsonval type constructed as shown in FIG. 3. The pivotedindicating needle, indicated at 41, cooperates with a scale 42calibrated directly in r.p.m. Secured to the needle is a moving coil 43which is rockable in the field of a permanent magnet 44, restoring forcebeing provided by springs 45. For the purpose of making electricalcontact upon achieving a predetermined r.p.m., meter contacts 50 areprovided consisting of a movable contact 51 which is mounted on thelower end of the indicating needle 41 and a. relatively fixed Contact 52which is adjustably interposed in the path of movement of the contact51. The movable contact 51 is preferably in the form of a few turns ofgood conducting flattened wire slidably mounted upon the lower extension53 of the needle. Thus, in addition to serving as a movable contact, themember 51, being slideably adjustable, serves as a counterweight for theneedle. It is of suflicient length as to insure engagement with thefixed contact 52 in all of its positions of adjustmentv For the purposeof mounting the fixed contact 52, an indicator or red line" pointer 55is used which is coaxially pivoted on a shaft 56 which is recessed inany opening formed coaxially in the meter cover glass. At its outer endthe shaft terminates in a limit setting knob 57 which at its inner endthe shaft has a registering connection with an arm 58 which mounts theadjustable contact 52. Any lost motion between the shaft 56 and arm 58is taken up by a small helical spring 59. The red line pointer 55 is setto indicate a predetermined limit r.p.m. on the scale 42 and the partsare so arranged that contact occurs when the needle 41 reaches suchr.p.m. level.

In accordance with one of the aspects of the present invention an outputrelay RY is provided having a disabling or grounding contact which isconnected by the disabling line D to the end of the primary winding 21of the ignition coil to make the ignition system inoperative, and meansincluding a capacitor are provided in a loop circuit so that closure ofthe meter contacts produces a powerful additive pulse of current throughthe meter coil forcefully bringing the contacts together in a lowresistance connection. Thus, referring to FIG. 2, a capacitor C1 isprovided which is connected at its left hand end to the meter contact 52and at its right hand end through a diode D to the right hand end of themeter coil 43. The loop is completed by an internal meter connection 61which extends from the movable contact 51 to the left hand end of themeter coil. for the purpose of making the capacitor C1 normally charged,a battery B is provided having, connected in series, a relatively highvalue resistor R3. A line 62 completes a connection from the battery tothe winding of the relay RY. The relay has normally open groundingcontacts K1 and K2, contacts Kl being connected via disabling line D tothe ignition coil.

Thus, as the speed of the engine increases, producing a proportionalincrease in current in the lines 36, 37, the needle 4] advances alongthe scale 42 until the pre-set limiting speed is reached, whereupon themovable contact 51 engages the fixed contact 52. Where initial touchingbetween the contacts is of an indecisive or chattering nature, as, forexample, where the rate of movement of the needle 41 is very slight asit eases into limit position, even tentative contact is sufficient toproduce an immediate avalanche of current from the discharging capacitorC1 through the meter coil 43, causing the coil to apply to the movablecontact a high level of torque so that the contacts are forcibly broughttogether to complete a low resistance connection through the battery andvia the line 62 to the coil of the relay RY. The discharge of thecapacitor, triggered by the initial contact between the meter contacts,produces an effect which may be likened to a high value of positivefeedback. While the peak current through the coil 43 may be high, itsduration is short because of low resistance in the discharge loop, whichproduces a short time constant. The capacitance of the capacitor C1 andthe voltage of the battery B are chosen so that the total energy contentof the current pulse is low enough so that no objectionable temperaturerise occurs in the meter coil 43. In a typical case the battery may havea voltage of 4.2 volts and the capacitor C] may have a capacitance of500 mfd.

It will be apparent that when the relay contacts K1 are closed the relay30 in the transmitter T is disabled along with the ignition coil so thatcurrent no longer flows in the output lines 36, 37 causing the needle 41in the meter to immediately drop back, thereby breaking contact betweenthe contacts 51, 52in the meter. Means are, however, provided forpreventing immediate drop-out of the output relay RY. This, inaccordance with the present invention, is brought about by providingcapacitor switching contacts, indicated at K2, to establish a chargingcircuit for the capacitor C] which includes the battery B, the coil ofthe output relay and an adjustable charging resistor, with the polarityof the connection being such that the charging current tends to maintainthe relay RY closed for an additional time interval which depends uponthe setting of the charging resistor. Thus referring to FIG. 2 it willbe noted that the charging circuit for capacitor C1, starting fromground, proceeds through switching contacts K2, charging resistor R1,capacitor C1, battery B to the coil of relay RY and back to ground. Theexistence of the diode D interposed between the charging circuit and themeter coil prevents the tachometer signal from T from being shuntedthrough resistor R3 and relay RY to ground during normal operation ofthe tachometer.

In order to be able to achieve a desired maximum dropout interval,which, in a practical case, may be up to one second in duration, whilenevertheless keeping the capacitor C1 to a level of capacitance which issafe as regards the meter coil 43, an auxiliary capacitor is employedwhich is charged during the time that the meter contacts are closed andwhich is additively discharged through the coil of the output relayafter the meter contacts open to assist in maintaining the output relaytemporarily closed. The auxiliary capacitor, indicated at C2, isconnected, through a charging resistor R2, between the capacitorswitching contacts K2 of the relay and the positive terminal of thebattery B. Thus when the meter contacts are closed, and contacts K2 areclosed, the capacitor C2 is charged to the polarity shown. A momentthereafter, when the meter contacts open, the capacitor C2 dischargesthrough capacitor switching contacts K2, through resistor R2 and line 62through the coil of the output relay RY to ground. Such dischargecurrent, being polarized the same as the charging or inrush current tothe capacitor C1, augments the effect of capacitor C1 in providing adesired drop-out interval. By varying the value of the resistor R1, andby proper choice of output relay RY, a matter well within the skill ofthe art, the dropout time interval may be set anywhere within a range ofapproximately O.l second to 1.0 second, or somewhat more if desired.

After the main capacitor C1 is substantially charged and the auxiliarycapacitor C2 substantially discharged, the current through the windingof the output relay will fall to a value which is no longer sufiicientto hold the armature in, and relay will drop out, opening the disablingcontacts K1 and removing the grounding circuit from the primary of theignition coil. The ignition coil will then be able to function as usualto build up the engine speed, once again, toward the limiting value. Itwill be apparent that the driver of the vehicle need no longer keep hiseye on the tachometer needle. He may simply floor the accelerator and bein readiness for clutching and shifting into the next higher gear assoon as he hears the engine falter at maximum speed, with the intervalthat the engine is depowered, by the holding in of relay RY, being justsufficient to permit a change of gears. This process is automaticallyrepeated through an entire set of gears from lowest to highest. Thefunction of the driver becomes simply the mechanical one of shifting aspromptly as possible during the de-powered intervals. The engine isworked at maximum average power short of a speed which will cause it toself-destruct with a high degree of reliability and safety and withoutexercise of any care or judgment on the part of the driver.

While the operation of the circuit shown in FIG. 2 will be apparent fromthe foregoing description, the operation may be summarized briefly inconnection with FIGS. 2a, 2b and 20 which set forth the three successivestates of the circuit during a typical cycle. In these figures theactive, or conductive, portions of the circuit are indicated by theheavy lines.

Referring to FIG. 2a, which shows the condition of the circuit uponinitial contact, the charge from capacitor C1 is discharged through thediode D into the meter coil 43. Current begins to flow from the batterythrough line 62 to the coil of the output relay, but the relay contactshave not yet closed because of the slight time delay which is inherentin any relay of the electromagnetic type.

FIG. 2b shows the effect of closure of the contacts K1, K2. The contactsKl ground the disabling line D. Closure of contacts K2 completes thecircuit through capacitor C2, resistor R2, battery B and meter contacts50 which, at that moment have not yet opened. Charging of the capacitorC2 takes place with great rapidity because of the relatively low timeconstant.

Since the grounding of the disabling line D disables the transmitter Tand shuts ofi current flow in lines 36, 37, and since the current fromthe capacitor C1 has spent itself, the current in the meter coil fallsabruptly, opening the meter contacts as shown in FIG. 2c. Contacts K2remain closed establishing a charging circuit for capacitor C1 viacharging resistor R1, capacitor C1, battery B and line 62 to the coil ofthe output relay RY. At the same time a discharge circuit for thecapacitor C2, shown dotted, may be traced through con tacts K2,capacitor C2, resistor R2 and line 62 to the relay coil. The respectivecharging and discharge currents are additive and serve to hold in therelay for a de-powered time inter val which depends upon the adjustmentof the resistor R1 (as well as the value of resistor R2). As soon as theinterval has expired and the capacitor currents have been dissipated,the current through the relay coil drops to a level which causes therelay to open, thereby opening the contacts K2 and the disablingcontacts K1, restoring the function of the ignition coil so that theengine is fully repowered and restoring operation of the tachometer,with the status of the circuit again being set forth in FIG. 2. In suchstate the capacitor C1 is fully charged and the capacitor C2 is fullydischarged in readiness for a new cycle when the engine speed againachieves its limiting value.

While the preferred form of the invention has particular utility inconnection with the operation of hot rod vehicles, it will be apparentthat the control system is not limited to such usage but is usefulwherever it is desired to de-power an engine for a predetermined timeinterval upon achieving a predetermined rotational speed. The system isnot intended for use on a highway where automatic de-powering may createrisk in a high speed traffic situation.

Typical'circuit values may be as follows:

Cl 500 mfd.

C2 500 mfd.

R1 500 ohms R2 470 ohms R3 10,000 ohms meter coil 160 ohms RY 65 ohmsBatt. B 4.2 volts 'Batt. 34 6.75 volts Cap. 35 0.16 mfd.

In one of the aspects of the invention it is, however, contemplated toturn oif the engine and to maintain it in the off condition untilintentionally reset. Thus, referring to FIG. 4 a modified engine controlsystem is disclosed in which the second set of contacts K2 on the relayare employed, not for capacitor switching purposes, but for sealing inpurposes to maintain the output relay energized, and the enginedepowered, indefinitely until the circuit is reset by a pressing of anormally closed push button. Thus, turning to FIG. 4 in whichcorresponding reference numerals, with the addition of a prime,represent corresponding parts, it will be seen that the relay contactsK2 are connected by a push button PB to the left hand or negative sideof the battery B thereby to maintain the battery B in the circuit of therelay coil. The operation of the circuit shown in FIG. 4 is similar tothat described above, in that closure of the meter contacts 50' uponachieving of a preset sped causes discharge of the capacitor C1 into thecoil 43 to bring the meter contacts forcibly together for immediate andpositive energization of the relay RY. Closure of the disabling contactsKl disables the engine and the tachometer transmitter so that the needle41' of the meter falls away from its maximum position breaking metercontacts 50'. However the sealing contacts K2, through the push buttonand battery, maintain output relay RY pulled until the sealing circuitis broken by momentarily pressing the push button.

Thus the arrangement shown in FIG. 4 performs a valuable protectivefunction wherever it is necessary or desirable to protect engine from anover speed condition as might result, for example, by the dropping ofthe load regardless of whether the engine is fixed, for example on atest stand, or in automotive usage.

It is one of the features of the invention, in both of the modificationsdiscussed above, that the same calibrated scale is used with the meterneedle for speed indication and with the red line pointer for speedlimitation. It will be apparent, how ever, that where only theprotective function is of interest the needle may be dispensed with butthe meter contacts retained for automatic de-powering. The term meter"as used in the claims is therefore employed in a general sense toinclude a sensitive calibrated relay. Also while it is preferred todisable the invention by grounding the primary of the ignition coil, itwill be apparent that the invention is not limited thereto and that anormally closed contact may be provided on the output relay in serieswith the regular ignition switch for open circuiting the ignition coilprimary when the relay is energized.

Finally while it is preferred to obtain positive feedback through themeter coil for achieving forcible engagement between the meter contacts,it will be apparent that such feedback may be achieved, withoutdeparting from the present invention, by making use of the inrushcurrent to a normally uncharged capacitor. An example of such anarrangement is shown in FIG. 5 in which similar components are indicatedby the same reference numerals as in FIG. 2, but doubly primed. Thus themain capacitor C1" instead of being effectively connected in parallelwith the battery and maintained normally charged may be in a loopcircuit which includes the battery and which is kept in a normallyuncharged state. When the limiting speed is achieved and contacts 50"close, current flows through a loop consisting the battery B", thecapacitor C1" and diode D" to the meter coil 43" causing the torqueexerted upon the meter contacts to be greatly increased to provide a lowresistance circuit, through the battery, to the relay RY". This causesclosure of contacts K1" and disabling of the ignition system andtachometer transmitter just as described, thereby opening the metercontacts. Simultaneous closure of capacitor switching contacts K2 withclosure of contacts K1 creates a capacitor discharging circuit throughresistor R1", the capacitor C1, and the coil of relay RY", causing therelay to hold in for an additional time interval, with the actual timeinterval depending upon the adjustment of the resistor R1. The relaythen drops out to repower the engine. The capacitor C1" is, at the endof such de-powering cycle, left in the uncharged state in readiness forrecharging when next the meter contacts close.

It will be apparent upon comparing the circuits of FIG. 2 and FIG. 5that the invention contemplates employing the inrush and outrushcurrents of the capacitor interchangeably. Thus in FIG. 2 it is thedischarge, or outrush, current of the capacitor C1 which makes forciblecontact within the meter and it is the inrush current, upon recharging,which is utilized to inhibit drop-out of the output relay. In FIG. 5,the situation is reversed; it is the inrush current of the capacitor C1which produces a high force level at the meter contacts and it is thesubsequent outrush which is utilized to inhibit dropout of the relay.

Because of the interchangeability in the utilization of inrush andoutrush capacitor currents, the term rush" current has been utilized asa generic term and is employed in the generic sense in the followingclaims.

I claim as my invention:

1. In a combined tachometer and maximum speed limiting device for anautomotive engine having a transmission as well as an ignition coil andbreaker points, the combination comprising a tachometer transmitterelectrically connected to the breaker points and having means forproducing a direct current output signal in accordance with enginespeed, a tachometer receiver in the form of a meter having a coilconnected to the transmitter driving a needle which cooperates with ascale calibrated in terms of engine speed, meter contacts including amovable contact on the needle and an adjustable contact cooperating withthe calibrated scale and adjustably interposable in the path of themovable contact for making contact when the speed reaches apredetermined level, an output relay having a coil and disablingcontacts controlled thereby, means for disablingly connecting thedisabling contacts to the ignition coil, a battery connected in serieswith the meter contacts and the relay coil, a capacitor charginglyconnected to the battery and connected in a loop circuit which includesthe meter coil and meter contacts so that when the meter contacts closeupon achieving the predetermined speed the capacitor rush currentthrough the meter coil urges the meter contacts forcibly togetherthereby to insure a reliable level of current flow to the relay coil sothat the engine is fully powered up to the predetermined speed andcompletely de-powered upon reaching the predetermined speed thereby tosignal to the driver that the engine is in condition for shifting to thenext speed of the transmission, and means for delaying drop-out of therelay for a predetermined time interval to pennit shifting by the driverinto the next higher speed of the transmission prior to the re-poweringof the engine which accompanies drop-out of the relay.

2. In a combined tachometer and disabling device for an automotiveengine having an ignition coil and ignition points, the combinationcomprising a tachometer transmitter coupled to the ignition coil andpoints and having means for producing a direct current output inaccordance with engine speed, a tachometer receiver in the form of ameter having a coil and a needle and calibrated in terms of enginespeed, meter contacts including a movable contact coupled to the needleand a relatively fixed but adjustable contact in the path of movementthereof for making contact when the speed reaches a predetermined level,a relay having a coil and first and second sets of relay contacts, abattery connected in series with the meter contacts and the relay coil,a capacitor connected in a loop circuit which includes the meter coiland meter contacts so that when the meter contacts close upon achievingthe predetermined speed capacitor rush current through the meter coilurges the meter contacts forcibly together thereby to insure a reliablelevel of current flow to the relay, the first set of relay contactsbeing connected to the ignition coil for disabling the same when therelay closes, the second set of relay contacts being connected in a loopcircuit which includes the capacitor, battery and relay coil so thatwhen the second set of relay contacts closes capacitor rush currentflows through the relay coil thereby to maintain the coil closed for apredetermined time interval with automatic resumption of the operationof the engine following such time interval.

3. The combination as claimed in claim 2 in which an adjustable resistoris interposed in series with the circuit of the capacitor so as topermit variation of the time interval during which the relay remainsclosed.

4. In a combination tachometer and disabling device for an automotiveengine having ignition coil, the combination comprising a tachometertransmitter coupled to the engine and having means for producing adirect current output in accordance with engine speed, a tachometerreceiver including a meter having a coil and a needle, meter contactsincluding a movable contact coupled to the needle and a relatively fixedbut adjustable contact in the path of movement thereof for makingcontact at a predetermined limiting speed, an output relay having a coiland relay contacts, a battery connected in series with the metercontacts and the relay coil, a capacitor chargingly connected to thebattery and connected in a loop circuit which includes the meter coiland meter contacts so that when the meter contacts close upon achievingthe predetermined speed capacitor rush current through the meter coilurges the meter contacts forcibly together thereby to insure a reliablelevel of current flow to the relay, and means connected to the relaycontacts for at least temporarily disabling the ignition coil andpreventing any further increase in engine speed above the predeterminedlevel.

5. The combination as claimed in claim 4 in which the transmitter iscoupled to the ignition coil so that when the ignition coil is disabledthe meter contacts in the tachometer receiver are opened permitting theoutput relay to drop out thereby permitting the engine to resumefunctioning after brief disnblcmcnt,

6. The combination as claimed in claim 4 in which means are provided forcausing the output relay to hold in for a predetermined and adjustabletime interval following the opening of the meter contacts so that theengine is disabled for a brief but predetermined time interval.

7. The combination as claimed in claim 4 in which one of the outputrelay contacts is connected in parallel with the meter contacts tomaintain the relay in closed condition.

8. The combination as claimed in claim 4 in which one of the outputrelay contacts is effectively connected in parallel with the metercontacts and which a normally closed switch is provided connected inseries with the relay coil for achieving drop-out upon momentary manualoperation of the switch.

9. In a combined tachometer and maximum speed device or the like, thecombination of a transmitter having means for producing a variabledirect current signal, a receiver in the form of a meter having a coiland a pivoted needle cooperating with a calibrated scale, meter contactsincluding a movable contact on the needle and a relatively fixed contactadjustably interposed in the path of movement thereof, means includingan electric circuit for responding to closure of the meter contacts, acapacitor, a battery for charging the capacitor, said capacitor beingconnected in a loop circuit including the coil and meter contacts withthe charge on the capacitor having a polarity which is the same as thepolarity of the signal current so that when the meter contacts close therush current of the capacitor flows through the coil in a direction tourge the meter contacts forcibly together thereby to insure the makingof positive contact for the responsive means.

10. In a combined tachometer and maximum speed device or the like, thecombination of a transmitter having means for producing a variabledirect current signal, a receiver in the form of a meter having a coiland a pivoted needle cooperating with a calibrated scale, meter contactsincluding a movable contact on the needle and a relatively fixed contactadjustably interposed in the path of movement thereof, means includingan electric circuit for responding to closure of the meter contacts, acapacitor, a battery and series resistor for charging the capacitor,said capacitor being connected in a loop circuit including the coil andmeter contacts with the charge on the capacitor having a polarity whichis the same as the polarity of the signal current so that when the metercontacts close the capacitor is discharged through the coil in adirection to urge the meter contacts forcibly together thereby to insurethe making of positive contact for the responsive means.

11. The combination as claimed in claim 9 in which the pivoted needlehas an arm extending beyond the pivot and in which the movable contactis in the form of a counterweight slidably adjustable on the arm, thefixed contact being so arranged as to make contact with the movablecontact in all of the adjusted positions of the latter.

12. The combination as claimed in claim 10 in which the capacitor isshunted by the battery with a high value charging resistor interposedfor maintenance of charge on the capacitor following the opening of therelay.

13. In a combined tachometer and maximum speed limiting device for anautomotive engine having an ignition coil and breaker points, thecombination comprising a tachometer transmitter coupled to the engineand having means for producing a direct current output signal inaccordance with engine speed, a tachometer receiver in the form of ameter having a coil connected to the transmitter driving a needle andcalibrated in terms of engine speed, meter contacts including a movablecontact on the needle and a relatively fixed contact adjustablyinterposed in the path of movement thereof for making contact when thespeed reaches a predetermined level, an output relay having a coil andignition disabling contacts as well as capacitor switching contacts, abattery connected in series with the meter contacts and the relay coil,a first capacitor connected in series with the meter contacts and metercoil so that when the meter contacts tentatively come together uponreaching the predetermined speed the capacitor is discharged through themeter coil to urge the meter contacts more forcibly together thereby toinsure a reliable level of current flow to the relay coil and promptclosure of the relay contacts, a second capacitor connected in serieswith the meter contacts, battery, and capacitor switching contacts sothat when the meter contacts and capacitor switching contacts close thesecond capacitor is charged, the second capacitor being connected inaddition in a loop circuit which includes the capacitor switchingcontacts and relay coil so that when the meter contacts subsequentlyopen the second capacitor is connected for discharge through the relaycoil to hold in the relay for a predetennined short time interval andmeans connected to the ignition disabling contacts for temporarilydisabling ignition.

14. In a combination tachometer and maximum speed limiting device for anautomotive engine having an ignition coil and breaker points, thecombination comprising a tachometer transmitter coupled to the breakerpoints and having means for producing a direct current output signal inaccordance with engine speed, a tachometer receiver in the form of ameter having a coil connected to the transmitter and driving a needleand calibrated in terms of engine speed, meter contacts including amovable contact on the pointer and a relatively fixed contact adjustablyinterposed in the path of movement thereof for making contact when thespeed reaches a predetermined level, an output relay having a coil andignition disabling contacts as well as capacitor switching contacts, abattery connected in series with the meter contacts and the relay coil,a capacitor connected in series with the meter contacts and meter coilso that when the meter contacts tentatively come together upon reachingthe predetermined speed the capacitor is discharged through the metercoil to urge the meter contacts forcibly together thereby to insure areliable level of current flow to the relay coil and prompt closure ofthe relay contacts, the capacitor having a charging resistor and acharging circuit which includes the capacitor switching contact,charging resistor, battery and relay coil so that closure of thecapacitor switching contact causes charging current to flow through therelay coil thereby to delay drop out of the relay when the metercontacts open, and means for coupling the ignition disabling contacts tothe circuit of the ignition coil for disabling the latter.

15. In a combined tachometer and maximum speed limiting device for anautomotive engine having an ignition coil and breaker points, thecombination comprising a tachometer transmitter connected to the breakerpoints and having means for producing a direct current output signal inaccordance with engine speed, a tachometer receiver in the form of ameter having a coil connected to the transmitter driving a pivotedneedle and calibrated in terms of engine speed, meter contacts includinga movable contact on the pointer and a relatively fixed but adjustablecontact interposed in the path of movement thereof for making contactwhen the speed reaches a predetermined level, an output relay having acoil and ignition disabling contacts as well as capacitor switchingcontacts, means connected to the disabling contacts for disabling theignition coil, a battery connected in series with the meter contacts andthe relay coil, a first normally charged capacitor connected in a loopcircuit which includes the meter contacts and meter coil so that whenthe meter contacts come together upon achieving the predetermined speedthe first capacitor is discharged through the meter coil to urge themeter contacts forcibly together, a second capacitor having a loopcircuit which includes the capacitor switching contacts, the battery,and the meter contacts for charging the second capacitor, the firstcapacitor having a charging resistor and a charging circuit whichincludes the capacitor switching contacts, the battery and relay coil sothat when the meter contacts open as a result of disabling of theignition charging cur rent passes through the relay coil to delaydrop-out of the relay, the second capacitor having a discharge circuitwhich includes the capacitor switching contacts and relay coil so thatwhen the meter contacts open the second capacitor is discharged throughthe relay coil for achieving additional delag in the dropout of therelay.

l In a combined tachometer and maximum speed limiting device for anautomotive engine having an ignition coil and breaker points thecombination comprising a tachometer transmitter electrically coupled tothe ignition points and hav ing means for producing a direct voltageoutput in accordance with engine speed, a tachometer receiver in theform of a meter having a coil connected to the transmitter and driving aneedle calibrated in terms of engine speed, meter contacts including amovable contact coupled to the needle and a relatively fixed contactadjustable interposed in the path of movement thereof for making contactwhen the speed reaches a predetermined level, an output relay having acoil and ignition disabling contacts as well as capacitor switchingcontacts, means for interconnecting the ignition disabling contacts andignition coil for disabling the latter, a battery connected in serieswith the meter contacts and the relay coil, a first capacitor connectedin a loop circuit which includes the meter coil and meter contacts sothat when the meter contacts close upon achieving the predeterminedspeed the first capacitor is discharged through the meter coil to urgethe meter contacts forcibly together thereby to insure a reliable levelof current flow to the relay coil, a second capacitor connected to themeter contacts and battery for charging when the meter contacts close,both of the capacitors being connected in loop circuits which includethe capacitor switching contacts and the relay coil so that when themeter contacts open incident to disabling the ignition coil the firstcapacitor is charged through the relay coil and the second capacitor isdischarged through the relay coil thereby to inhibit drop-out of therelay for a delay interval.

17. The combination as claimed in claim 16 in which the capacitors eachhave a series resistor for determining the drop-out delay interval.

1. In a combined tachometer and maximum speed limiting device for anautomotive engine having a transmission as well as an ignition coil andbreaker points, the combination comprising a tachometer transmitterelectrically connected to the breaker points and having means forproducing a direct current output signal in accordance with enginespeed, a tachometer receiver in the form of a meter having a coilconnected to the transmitter driving a needle which cooperates with ascale calibrated in terms of engine speed, meter contacts including amovable contact on the needle and an adjustable contact cooperating withthe calibrated scale and adjustably interposable in the path of themovable contact for making contact when the speed reaches apredetermined level, an output relay having a coil and disablingcontacts controlled thereby, means for disablingly connecting thedisabling contacts to the ignition coil, a battery connected in serieswith the meter contacts and the relay coil, a capacitor charginglyconnected to the battery and connected in a loop circuit which includesthe meter coil and meter contacts so that when the meter contacts closeupon acHieving the predetermined speed the capacitor rush currentthrough the meter coil urges the meter contacts forcibly togetherthereby to insure a reliable level of current flow to the relay coil sothat the engine is fully powered up to the predetermined speed andcompletely depowered upon reaching the predetermined speed thereby tosignal to the driver that the engine is in condition for shifting to thenext speed of the transmission, and means for delaying drop-out of therelay for a predetermined time interval to permit shifting by the driverinto the next higher speed of the transmission prior to the re-poweringof the engine which accompanies drop-out of the relay.
 2. In a combinedtachometer and disabling device for an automotive engine having anignition coil and ignition points, the combination comprising atachometer transmitter coupled to the ignition coil and points andhaving means for producing a direct current output in accordance withengine speed, a tachometer receiver in the form of a meter having a coiland a needle and calibrated in terms of engine speed, meter contactsincluding a movable contact coupled to the needle and a relatively fixedbut adjustable contact in the path of movement thereof for makingcontact when the speed reaches a predetermined level, a relay having acoil and first and second sets of relay contacts, a battery connected inseries with the meter contacts and the relay coil, a capacitor connectedin a loop circuit which includes the meter coil and meter contacts sothat when the meter contacts close upon achieving the predeterminedspeed capacitor rush current through the meter coil urges the metercontacts forcibly together thereby to insure a reliable level of currentflow to the relay, the first set of relay contacts being connected tothe ignition coil for disabling the same when the relay closes, thesecond set of relay contacts being connected in a loop circuit whichincludes the capacitor, battery and relay coil so that when the secondset of relay contacts closes capacitor rush current flows through therelay coil thereby to maintain the coil closed for a predetermined timeinterval with automatic resumption of the operation of the enginefollowing such time interval.
 3. The combination as claimed in claim 2in which an adjustable resistor is interposed in series with the circuitof the capacitor so as to permit variation of the time interval duringwhich the relay remains closed.
 4. In a combination tachometer anddisabling device for an automotive engine having ignition coil, thecombination comprising a tachometer transmitter coupled to the engineand having means for producing a direct current output in accordancewith engine speed, a tachometer receiver including a meter having a coiland a needle, meter contacts including a movable contact coupled to theneedle and a relatively fixed but adjustable contact in the path ofmovement thereof for making contact at a predetermined limiting speed,an output relay having a coil and relay contacts, a battery connected inseries with the meter contacts and the relay coil, a capacitorchargingly connected to the battery and connected in a loop circuitwhich includes the meter coil and meter contacts so that when the metercontacts close upon achieving the predetermined speed capacitor rushcurrent through the meter coil urges the meter contacts forciblytogether thereby to insure a reliable level of current flow to therelay, and means connected to the relay contacts for at leasttemporarily disabling the ignition coil and preventing any furtherincrease in engine speed above the predetermined level.
 5. Thecombination as claimed in claim 4 in which the transmitter is coupled tothe ignition coil so that when the ignition coil is disabled the metercontacts in the tachometer receiver are opened permitting the outputrelay to drop out thereby permitting the engine to resume functioningafter brief disablement.
 6. The combination as claimed in claim 4 inwhich means aRe provided for causing the output relay to hold in for apredetermined and adjustable time interval following the opening of themeter contacts so that the engine is disabled for a brief butpredetermined time interval.
 7. The combination as claimed in claim 4 inwhich one of the output relay contacts is connected in parallel with themeter contacts to maintain the relay in closed condition.
 8. Thecombination as claimed in claim 4 in which one of the output relaycontacts is effectively connected in parallel with the meter contactsand which a normally closed switch is provided connected in series withthe relay coil for achieving drop-out upon momentary manual operation ofthe switch.
 9. In a combined tachometer and maximum speed device or thelike, the combination of a transmitter having means for producing avariable direct current signal, a receiver in the form of a meter havinga coil and a pivoted needle cooperating with a calibrated scale, metercontacts including a movable contact on the needle and a relativelyfixed contact adjustably interposed in the path of movement thereof,means including an electric circuit for responding to closure of themeter contacts, a capacitor, a battery for charging the capacitor, saidcapacitor being connected in a loop circuit including the coil and metercontacts with the charge on the capacitor having a polarity which is thesame as the polarity of the signal current so that when the metercontacts close the rush current of the capacitor flows through the coilin a direction to urge the meter contacts forcibly together thereby toinsure the making of positive contact for the responsive means.
 10. In acombined tachometer and maximum speed device or the like, thecombination of a transmitter having means for producing a variabledirect current signal, a receiver in the form of a meter having a coiland a pivoted needle cooperating with a calibrated scale, meter contactsincluding a movable contact on the needle and a relatively fixed contactadjustably interposed in the path of movement thereof, means includingan electric circuit for responding to closure of the meter contacts, acapacitor, a battery and series resistor for charging the capacitor,said capacitor being connected in a loop circuit including the coil andmeter contacts with the charge on the capacitor having a polarity whichis the same as the polarity of the signal current so that when the metercontacts close the capacitor is discharged through the coil in adirection to urge the meter contacts forcibly together thereby to insurethe making of positive contact for the responsive means.
 11. Thecombination as claimed in claim 9 in which the pivoted needle has an armextending beyond the pivot and in which the movable contact is in theform of a counterweight slidably adjustable on the arm, the fixedcontact being so arranged as to make contact with the movable contact inall of the adjusted positions of the latter.
 12. The combination asclaimed in claim 10 in which the capacitor is shunted by the batterywith a high value charging resistor interposed for maintenance of chargeon the capacitor following the opening of the relay.
 13. In a combinedtachometer and maximum speed limiting device for an automotive enginehaving an ignition coil and breaker points, the combination comprising atachometer transmitter coupled to the engine and having means forproducing a direct current output signal in accordance with enginespeed, a tachometer receiver in the form of a meter having a coilconnected to the transmitter driving a needle and calibrated in terms ofengine speed, meter contacts including a movable contact on the needleand a relatively fixed contact adjustably interposed in the path ofmovement thereof for making contact when the speed reaches apredetermined level, an output relay having a coil and ignitiondisabling contacts as well as capacitor switching contacts, a batteryconnected in series with the meter contacts and the relay coil, A firstcapacitor connected in series with the meter contacts and meter coil sothat when the meter contacts tentatively come together upon reaching thepredetermined speed the capacitor is discharged through the meter coilto urge the meter contacts more forcibly together thereby to insure areliable level of current flow to the relay coil and prompt closure ofthe relay contacts, a second capacitor connected in series with themeter contacts, battery, and capacitor switching contacts so that whenthe meter contacts and capacitor switching contacts close the secondcapacitor is charged, the second capacitor being connected in additionin a loop circuit which includes the capacitor switching contacts andrelay coil so that when the meter contacts subsequently open the secondcapacitor is connected for discharge through the relay coil to hold inthe relay for a predetermined short time interval and means connected tothe ignition disabling contacts for temporarily disabling ignition. 14.In a combination tachometer and maximum speed limiting device for anautomotive engine having an ignition coil and breaker points, thecombination comprising a tachometer transmitter coupled to the breakerpoints and having means for producing a direct current output signal inaccordance with engine speed, a tachometer receiver in the form of ameter having a coil connected to the transmitter and driving a needleand calibrated in terms of engine speed, meter contacts including amovable contact on the pointer and a relatively fixed contact adjustablyinterposed in the path of movement thereof for making contact when thespeed reaches a predetermined level, an output relay having a coil andignition disabling contacts as well as capacitor switching contacts, abattery connected in series with the meter contacts and the relay coil,a capacitor connected in series with the meter contacts and meter coilso that when the meter contacts tentatively come together upon reachingthe predetermined speed the capacitor is discharged through the metercoil to urge the meter contacts forcibly together thereby to insure areliable level of current flow to the relay coil and prompt closure ofthe relay contacts, the capacitor having a charging resistor and acharging circuit which includes the capacitor switching contact,charging resistor, battery and relay coil so that closure of thecapacitor switching contact causes charging current to flow through therelay coil thereby to delay drop out of the relay when the metercontacts open, and means for coupling the ignition disabling contacts tothe circuit of the ignition coil for disabling the latter.
 15. In acombined tachometer and maximum speed limiting device for an automotiveengine having an ignition coil and breaker points, the combinationcomprising a tachometer transmitter connected to the breaker points andhaving means for producing a direct current output signal in accordancewith engine speed, a tachometer receiver in the form of a meter having acoil connected to the transmitter driving a pivoted needle andcalibrated in terms of engine speed, meter contacts including a movablecontact on the pointer and a relatively fixed but adjustable contactinterposed in the path of movement thereof for making contact when thespeed reaches a predetermined level, an output relay having a coil andignition disabling contacts as well as capacitor switching contacts,means connected to the disabling contacts for disabling the ignitioncoil, a battery connected in series with the meter contacts and therelay coil, a first normally charged capacitor connected in a loopcircuit which includes the meter contacts and meter coil so that whenthe meter contacts come together upon achieving the predetermined speedthe first capacitor is discharged through the meter coil to urge themeter contacts forcibly together, a second capacitor having a loopcircuit which includes the capacitor switching contacts, the battery,and the meter contacts for charging the second capaciTor, the firstcapacitor having a charging resistor and a charging circuit whichincludes the capacitor switching contacts, the battery and relay coil sothat when the meter contacts open as a result of disabling of theignition charging current passes through the relay coil to delaydrop-out of the relay, the second capacitor having a discharge circuitwhich includes the capacitor switching contacts and relay coil so thatwhen the meter contacts open the second capacitor is discharged throughthe relay coil for achieving additional delay in the drop-out of therelay.
 16. In a combined tachometer and maximum speed limiting devicefor an automotive engine having an ignition coil and breaker points thecombination comprising a tachometer transmitter electrically coupled tothe ignition points and having means for producing a direct voltageoutput in accordance with engine speed, a tachometer receiver in theform of a meter having a coil connected to the transmitter and driving aneedle calibrated in terms of engine speed, meter contacts including amovable contact coupled to the needle and a relatively fixed contactadjustable interposed in the path of movement thereof for making contactwhen the speed reaches a predetermined level, an output relay having acoil and ignition disabling contacts as well as capacitor switchingcontacts, means for interconnecting the ignition disabling contacts andignition coil for disabling the latter, a battery connected in serieswith the meter contacts and the relay coil, a first capacitor connectedin a loop circuit which includes the meter coil and meter contacts sothat when the meter contacts close upon achieving the predeterminedspeed the first capacitor is discharged through the meter coil to urgethe meter contacts forcibly together thereby to insure a reliable levelof current flow to the relay coil, a second capacitor connected to themeter contacts and battery for charging when the meter contacts close,both of the capacitors being connected in loop circuits which includethe capacitor switching contacts and the relay coil so that when themeter contacts open incident to disabling the ignition coil the firstcapacitor is charged through the relay coil and the second capacitor isdischarged through the relay coil thereby to inhibit drop-out of therelay for a delay interval.
 17. The combination as claimed in claim 16in which the capacitors each have a series resistor for determining thedrop-out delay interval.